[ res-puh-rey-shuhn ]
See synonyms for respiration on
  1. the act of respiring; inhalation and exhalation of air; breathing.

  2. Biology.

    • the sum total of the physical and chemical processes in an organism by which oxygen is conveyed to tissues and cells, and the oxidation products, carbon dioxide and water, are given off.

    • an analogous chemical process, as in muscle cells or in anaerobic bacteria, occurring in the absence of oxygen.

Origin of respiration

1400–50; late Middle English respiracioun<Latin respīrātiōn- (stem of respīrātiō) a breathing out, equivalent to respīrāt(us) (past participle of respīrāre to respire) + -iōn--ion

Other words from respiration

  • res·pi·ra·tion·al, adjective
  • pre·res·pi·ra·tion, noun

Words Nearby respiration Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use respiration in a sentence

British Dictionary definitions for respiration


/ (ˌrɛspəˈreɪʃən) /

  1. the process in living organisms of taking in oxygen from the surroundings and giving out carbon dioxide (external respiration). In terrestrial animals this is effected by breathing air

  2. the chemical breakdown of complex organic substances, such as carbohydrates and fats, that takes place in the cells and tissues of animals and plants, during which energy is released and carbon dioxide produced (internal respiration)

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for respiration


[ rĕs′pə-rāshən ]

  1. The process by which organisms exchange gases, especially oxygen and carbon dioxide, with the environment. In air-breathing vertebrates, respiration takes place in the lungs. In fish and many invertebrates, respiration takes place through the gills. Respiration in green plants occurs during photosynthesis.

The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Cultural definitions for respiration


The conversion of oxygen by living things into the energy by which they continue life. Respiration is part of metabolism.

Notes for respiration

Carbon dioxide is a waste product of respiration.

The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.